‘Units’ as meter / liter / m² / m³…. or translated to ‘Einheit’. A piece or number of pieces is ‘Stück’. So you can have ‘5 Stück’ of a product, each 3 m long and with m as unit of price, then there will be 15 ‘Einheiten’.

I’m actually doing a project in Germany and I have noted that “unit(s)" has been translated by Einheit(en). This sounds quite unusual for me, as I’m used to the word “Stück” to describe the number of pieces. My customer is also puzzled about the word Einheit(en) as it does not fit to his vocabulary. At least in Switzerland, I always used the word “Stück” for material.